Art Liscano knows he's an endangered species in the job market: He's a meter reader in Fresno, Calif. For 26 years, he's driven from house to house, checking how much electricity Pacific Gas & Electric customers have used.

But PG&E doesn't need many people like Liscano making rounds anymore. Every day, the utility replaces 1,200 old-fashioned meters with digital versions that can collect information without human help, generate more accurate power bills, even send an alert if the power goes out.

"I can see why technology is taking over," says Liscano, 66, who earns $67,000 a year. "We can see the writing on the wall." His department employed 50 full-time meter readers just six years ago. Now, it has six.

Smart machines may replace jobs like meter readers and assembly line workers but they cannot replace jobs in the trades like plumbers and electricians and those that repair the smart machines. Get a trade, young man.